Cisco Switch 3850 model : SSH Connection Refused, network error.

[Tosin Ola]

Hi ,

I have been troubleshooting this switch 3850 about 3 days now but still no luck. The switch cannot connect remotely through SSH. 

i did sh ip ssh command:

RESULT
SSH Disabled - version 2.0
%Please create RSA keys to enable SSH (and of atleast 768 bits for SSH v2).
Authentication methods:publickey,keyboard-interactive,password
Authentication Publickey Algorithms:x509v3-ssh-rsa,ssh-rsa
Hostkey Algorithms:x509v3-ssh-rsa,ssh-rsa
Encryption Algorithms:aes256-ctr
MAC Algorithms:hmac-sha1-96
KEX Algorithms:diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
Authentication timeout: 120 secs; Authentication retries: 3
Minimum expected Diffie Hellman key size : 2048 bits
IOS Keys in SECSH format(ssh-rsa, base64 encoded): NONE

#sh ssh
%No SSHv2 server connections running.

LINE VTY CONFIG

line con 0
stopbits 1
line aux 0
stopbits 1
line vty 0 4
password 7 0239532B1E312145
authorization exec AAA
accounting commands 15 AAA
login authentication AAA
transport input ssh
transport output ssh
line vty 5 15
password 7  0239532B1E312145
authorization exec AAA
accounting commands 15 AAA
login authentication AAA
transport input ssh
transport output ssh

Please what am i doing wrong.  I really need this switch to work as client are putting more pressure on me.

[Mark Malone]

hi

you have no key create it cehck again show ip ssh

%Please create RSA keys to enable SSH (and of atleast 768 bits for SSH v2).

(config)#crypto key generate rsa

hit return and type 2048 and hit return again

then run show ip ssh again

[Tosin Ola]

i have generated crypto key using modulus 768 and 1024 .

I will try and use 2048 bit and see how it goes

[Mark Malone]

If it doesnt work post what you see exactly , in case something else is happening but currently without a Key you wont get an SSH

[Jaderson Pessoa]

Hello, do it:

sw(config): username teste privilege 15 secret testin@123 (create a batter than this exemple)
sw(config): crypto key generate rsa modulus 2048
sw(config): ssh version 2
sw(config): line vty 0 15
sw(config-if): transport input ssh

test your connection again.

here you will find a good documentation about this process: https://www.cisco.com/c/en/us/support/docs/security-vpn/secure-shell-ssh/4145-ssh.html

[Tosin Ola · Accepted solution]

Below is the commad i used :

no ip ssh rsa keypair-name sshkey

ip ssh server algorithm mac hmac-sha2-512 hmac-sha2-256 hmac-sha1-96 hmac-sha1

ip ssh server algorithm encryption aes256-ctr aes192-ctr aes128-ctr

crypto key generate rsa [Modulus 1024]

sh ip ssh [SSH Enabled v2.0]